This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this project is to perform biochemical characterization of proteins that modulate the activity of channels important for pain sensation. The targets of study will include channel cytoplasmic domains, small molecule modulators, and peptide modulators. The objective is to purify proteins, determine molecular interaction sites, and perform structural studies.The UCSF mass spectrometry facility will aid us in determining the accurate mass of purified products and confirming the identity of purified products. The aid of the facility will also allow us to interpret results from chemical crosslinking studies in the future.